Automotive vapor choke

ABSTRACT

An automotive vapor choke for association with a carburetion system for an internal combustion engine of the type directing a predetermined air-fuel mixture to an intake manifold of an internal combustion engine wherein intake engine manifold vacuum produced during engine cranking is used to draw fuel vapors from the fuel supply of a vehicle to precharge the intake manifold with vaporized fuel and air prior to ignition. The system includes two parallel vapor conduits connected to vapor sources in the fuel supply and to a vapor enrichment port located between the carburetor throttle and the intake manifold. A solenoid is conditioned during engine cranking to close the throttle to increase the intake manifold vacuum thus increasing precharge vapor flow. After the engine starts, the solenoid is conditioned to open the throttle to a normal idle position so as to direct a predetermined air-fuel mixture from the carburetor to the intake manifold and valve means in the parallel lines are conditioned to reduce the flow of fuel vapors from the tank to the intake manifold to reduce fuel vapor enrichment of the fuel supply to the engine.

United States Patent 1 Van Dusen, III et al.

[ June 3, 1975 AUTOMOTIVE VAPOR CHOKE [75] Inventors: Henry J. Van Dusen, 111,

Huntington Woods; Paul T. Vickers, Royal Oak, both of Mich.

[73] Assignee: General Motors Corporation,

Detroit, Mich.

[22] Filed: Apr. 12, 1974 [21] App]. No.: 460,442

[52] US. Cl. 123/136; 123/179 BG; 123/179 G [51] Int. Cl. F02m 59/00 [58] Field of Search 123/136, 179 G, 179 B6 [56] References Cited I UNITED STATES PATENTS 3,610,221 10/1971 Stoltman 123/136 3,646,731 3/1972 Hansen 123/136 3,675,634 7/1972 Tatsutomi 123/136 3,683,597 8/1972 Beveridge 123/136 3,683,878 8/1972 Rogers 123/136 8/1973 Hollis 123/136 Primary Examine rManuel A. Antonakas Assistant Examiner-Daniel J. OConnor Attorney, Agent, or FirmJ. C. Evans [57] ABSTRACT An automotive vapor choke for association with a carburetion system for an internal combustion engine of the type directing a predetermined air-fuel mixture to an intake manifold of an internal combustion engine wherein intake engine manifold vacuum produced during engine cranking is used to draw fuel vapors from the fuel supply of a vehicle to precharge the intake manifold with vaporized fuel and air prior to ignition. The system includes two parallel vapor conduits connected to vapor sources in the fuel supply and to a vapor enrichment port located between the carburetor throttle and the intake manifold. A solenoid is conditioned during engine cranking to close the throttle to increase the intake manifold vacuum thus increasing precharge vapor flow. After the engine starts, the solenoid is conditioned to open the throttle to a normal idle position so as to direct a predetermined air-fuel mixture from the carburetor to the intake manifold and valve means in the parallel lines are conditioned to reduce the flow of fuel vapors from the tank to the intake manifold to reduce fuel vapor enrichment of the fuel supply to the engine.

3 Claims, 1 Drawing Figure AUTOMOTIVE VAPOR CHOKE This invention relates to air-fuel supply systems for internal combustion engines and more particularly to a vapor fuel enrichment system for supplementing a predetermined air-fuel mixture directed into the intake manifold of an internal combustion engine from a conventional carburetor assembly.

Under cold engine start conditions. existing carburetors are programmed to produce a flow of enriched mixture into the intake manifold. It is observed that CO and hydrocarbon emissions from the engine are elevated during this period due in part to the presence of liquid fuel components in the cold start mixture.

One proposal for reducing liquid fuel passage to the combustion cylinders of an engine under cold start conditions is the provision of a manifold crossover passage way and a heat conductive plate interposed between the exhaust manifold cross-over passageway and the inlet to the intake manifold. Such an arrangement serves to evaporate such liquid fuel particles prior to passage into the intake manifold runners. Such systems, however, are ineffective during the engine cranking mode since exhaust heat is produced only after engine ignition occurs.

Accordingly, an object of the present invention is to improve initial combustion of the fuel supply to an internal combustion engine by the provision of a vapor choke system including means for conditioning a throttle of a conventional carburetor to a closed position during engine cranking so that the engine cranking action will produce a reduced vacuum in the intake manifold; and further including means for communicating the intake manifold during the cranking operation with a vaporized fuel air source to cause a precharge of vaporized fuel and air in the intake manifold prior to engine ignition to improve engine combustion at start and to reduce engine emissions; and by still further including means to condition the system for conventional flow ofa predetermined fuel air supply from a carburetor into the manifold a predetermined time period after engine ignition to maintain smooth engine idle opera tion.

Still another object of the present invention is to provide an improved vapor choke system for association with a conventional carburetor supplying a predetermined air-fuel ratio to the intake manifold of an internal combustion engine and wherein a throttle valve is used to regulate the air-fuel supply to the engine in accordance with vehicle operating conditions by the provision. of a solenoid means to position the throttle closed during the engine cranking mode to increase the vacuum in an engine intake manifold and to include flow control means for connecting a source of vaporized fuel and air to an unrestricted vapor port between the closed throttle and the intake manifold to cause flow from the source into the intake manifold to precharge the manifold with an easily combustible mixture during the cranking mode and conditioning the throttle solenoid means and flow means when the engine has started to supply a required air-fuel supply from a conventional carburetor to the engine and to modulate vapor flow from the source to prevent excessive fuel enrichment so as to maintain smooth engine edle operation.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawing wherein a preferred embodiment of the present invention is clearly shown.

The single drawing is a diagrammatic view of an automotive vapor choke system including an enlarged sectional view of a carburetor and a fragmentary side elevational view of a throttle position solenoid of the present invention.

Referring now to the drawing, in FIG. 1 a fuel supply system 10 is illustrated including a conventional airfuel supply carburetor 12 having a bore 14 therethrough with an upper open inlet 16 adapted to be connected to an air cleaner (not shown) and a lower open end 18 adapted to be connected to an intake manifold 20.

The bore 14 has a throttle valve 22 pivotally supported therein with an operating shaft 24 connected thereto with its shaft 24 coupled to an operating lever 26, shown at the bottom of the drawing, which is connected to suitable throttle linkage means 28. A throttle position solenoid has a plunger 32 that engages a land 34 on lever 26 to position valve 22 in a curb idle position. Spring 35 biases lever 26 to position valve 22 closed when the solenoid is deenergized.

The carburetor 12 includes an unrestricted vapor supply port 36 therein associated with a vaporized airfuel supply system 37 including a vehicle fuel tank 38 having a vaporized fuel and air space 39 located thereabove defining part of a vaporized fuel supply for the port 36. Additionally, the system includes a charcoal canister 40 filled with a suitable vapor adsorbing active material 42 such as silica gel or activated charcoal. The canister 40 has an inlet 44 and a vent conduit 46 thererom. The inlet 44 is connected to a conduit 48 that is communicated with the space 39 of the tank 38 across a restriction defined by orifice 50 and is further connected to a vapor supply conduit 52 having a high rate v-apor control solenoid valve 54 therein and an outlet branch 56 that communicates with an inlet conduit 58 to the port 36. A solenoid valve 60 upstream of the supply conduit 58 is positioned to control vapor flow from a supply conduit 62 that is in communication with the fuel tank vapor space 39 through a port 64 in the tank 38.

A control circuit for valves 54, 60 includes an ignition key-operated switch 66 for connecting a power source 68 with a coil 70 when the ignition key is in a run position. Coil 70, when energized, operates the throttle position solenoid 30 so that plunger 32 will position lever 26 and valve 22 in a curb idle position. The circuit further includes a conductor 72 with an ignition key-operated switch 73 maintained closed when the ignition is in a cranking position to energize a coil 74 that operates the solenoid valve 54. The solenoid valve 54 is conditioned during engine cranking to be energized so as to communicate the charcoal canister 40 with the port 36. Additionally, the circuit includes a conductor 76 in series connection with the switch 73 and a normally closed thermally responsive control switch 78 in conductor 79 for energizing a coil 80 to condition the solenoid valve 60 either opened or closed in accordance with engine temperature.

The carburetor 12 used in association with the system 10 of the present invention is representatively shown as a conventional carburetor of the type operated to provide a predetermined air-fuel mixture to the intake manifold of a vehicle in accordance with a choke setting, and positioning of a throttle during vehicle operation.

The main venturi section 84 in bore 14 is associated with a boost venturi 86 of conventional form. Fuel supply is from a fuel bowl 88. Under idle conditions, fuel air supply is through an idle tube 90 that has a top air bleed 92 and a lower air bleed 94 to direct air into the idle fuel within an idle channel 96 thence across an idle mixture needle 98 and an idle discharge hole 100 lo cated below the throttle plate 22 within the bore 14. The fuel supply through the idle discharge hole 100 combines with air flow through the bore 14 under idle conditions to produce a first predetermined air-fuel supply to the intake manifold 20. A second predetermined air-fuel supply is under the control of a main metering system 102 of conventional form.

In the present invention, the aforedescribed carburetor 12 which omits the choke valve of a conventional carburetor includes means for supplying a predetermined air-fuel mixture to an intake manifold after the engine is warmed-up. The carburetor operation is modified, under cold engine start operations, to produce an improved combustible mixture within the intake manifold that will improve engine starting characteristics and will further improve combustion of predetermined air-fuel mixtures from the carburetor 12 to reduce engine emissions.

Thus, when the vehicle is started under cold conditions, the ignition switch 66 is opened to cause the throttle valve to be biased closed by spring 35 connected to lever 26 as shown in FIG. 2. Switch 73 is closed to energize the coils 74, 80 of the solenoid valves 54, 60. Accordingly, during engine cranking operation with the throttle valve 22 closed, the intake manifold vacuum will be increased because of engine cylinder pumping action to draw vaporized fuel components from the fuel tank space 39. Concurrently, a reverse purge flow of air from the vent line 46 is directed through the material 42 within the charcoal vapor collection canister 40 and thence through the parallel con duits 56, 58 to direct a precharge of vaporized fuel and air into the intake manifold without directing air and fuel through the bore 14 of the conventional carburetor 12. The vaporized precharge of air and fuel in the intake manifold 20 is readily combustible in the engine cylinders to produce quick engine start and reduced engine emissions at cold start.

As soon as the engine starts, the switch 73 will open to deenergize the solenoid valve 54. The switch 66 closes at engine start to energize solenoid 30. This causes valve 22 to assume its curb idle position to communicate the bore 14 with the intake manifold 20 whereby the predetermined air-fuel supply of the carburetor 12 under idle conditions will be directed into the manifold 20. Since valve 54 is closed, excessive engine enrichment is avoided following engine ignition and to maintain smooth engine, the solenoid valve 60 is opened under control of switch 78 and the vapor flow into the intake manifold 20 is only from the tank space 39. The flow of vapors from the space 39 will mix with the predetermined air-fuel ratio from the carburetor 12 to produce improved mixing of the predetermined airfuel mixture and with an assured vapor phase of fuel to maintain improved combustion of fuel within the engine cylinders during the initial stage of engine combustion. Once the engine has reached a predetermined operating temperature wherein the predetermined airfuel mixture from the carburetor 12 will be adequately vaporized as it is directed through the intake manifold 20, the thermally responsive switch 78 will open to deenergize the solenoid valve to terminate the flow of vapor fuel components into the intake manifold from the vapor supply 34.

The sequenced energization of the valves 54, 60 constitutes a controlled modulation of vapor flow into the intake manifold 20 that will produce a first stage of enrichment under engine cranking operations wherein the fuel supply to the intake manifold 20 is in vapor form for improved combustion. When ignition is attained and cranking mode terminates, the vapor supply 34 is modulated further to a reduced level for sustaining positive combustion until the engine warms up. The third phase of modulation produced by the control system is attained when the engine has reached an operating temperature to vaporize liquid components of the predetermined air-fuel supply from the carburetor 12 at which time the vapor flow from the system 64 is terminated by closing the valve 60.

Test results have been conducted on a 1972 Oldsmobile with a 455 CID engine with standard emission controls and a carburetor modified to remove the production choke.

A comparison of 1972 FTP exhaust emissions with the production choke system and the vapor choke system is shown in the following table. The invention results in a substantial improvement in overall exhaust emissions of CO, HC and N0 The test vehicle was a well tuned 1972 production vehicle with a standard 1972 emission control system. An even greater percentage improvement would be anticipated if this car had been equipped with advanced emmission controls While the embodiments of the present invention, as herein disclosed, constitute a preferred form, it is to be understood that other forms might be adopted.

What is claimed is:

1. In a vapor choke system for an internal combustion engine of the type including a throttle controlled air-fuel supply carburetor for fuel flow to an intake manifold the improvement comprising: means including a throttle position solenoid for closing the throttle during engine cranking operations, means defining a vapor port in communication with the intake manifold, a vaporized fuel air source, first vapor supply means having valve means therein to direct vapor from said source to said port, said valve means being conditioned opened when the throttle is closed to cause intake manifold vacuum produced by engine cranking to draw vapors from said source to produce a precharge of vaporized air-fuel in the intake manifold during engine cranking so as to produce improved cylinder combustion at engine start, and means responsive to engine start to condition said throttle positioning solenoid to open said throttle to a curb idle position, and means to sequentially modulate further vaporized air-fuel flow from said source to modulate the richness of fuel flow to the intake manifold in accordance with engine operating conditions.

2. An automotive vapor choke control system for an internal combustion engine comprising: a carburetor having a bore directed therethrough including an inlet end adapted to be connected to a source of air and an outlet end adapted to be connected to an intake manifold of a vehicle, a throttle valve located within said bore above said manifold, means for directing air-fuel mixture into said bore in accordance with engine operating conditions to provide a first predetermined airfuel mixture flow into the intake manifold, means for positioning said throttle valve closed upon engine cranking operation, means defining a vapor port in communication with said bore between said throttle valve and the intake manifold, a source of vaporized fuel and air, first vapor supply means including valve means therein to control flow of vapor from said source to the vapor port, said valve means being conditioned to communicate said vapor port with said source of vaporized fuel and air when said throttle is closed whereby reduced intake manifold pressure produced by engine cranking operation will draw vapor from said source into said manifold to produce a vaporized precharge of fuel vapor in the intake manifold space during engine cranking so as to improve cylinder combustion at engine start, means responsive to engine ignition to open said throttle to a curb idle position, and means to produce a sequential control of vapor flow from said source to said vapor port so as to modulate the quantity of vapor fuel enrichment within said intake manifold in accordance with engine operating conditions.

3. A vapor choke system for an internal combustion engine comprising: an intake manifold for supplying air-fuel mixture to the cylinders of an internal combustion engine, a carburetor for directing a first predetermined mixture of air and fuel into said intake manifold including a mechanically positioned throttle valve for regulating the amount of said first predetermined airfuel mixture into the intake manifold, means for positioning said throttle valve closed during engine cranking operation, a vapor port located between said throttle valve in said intake manifold, a first vapor fuel source defined by a space within a fuel tank, a first conduit connected at opposite ends thereof to said space and said vapor port, first valve means in said conduit for controlling vapor flow between said fuel tank space and said vapor port, a vapor collection canister having vapor adsorbing material therein, means for communicating said canister with said fuel tank space to cause vapor generated therefrom to be bled to said charcoal canister during a fuel vapor recovery phase of operation, means defining a purge line connected to said canister for back flow of air through said canister for removing adsorbed fuel vapors therefrom during a purge cycle of operation, and a second conduit connected to said canister and to said vapor port, said second conduit having second valve means therein, said first and second valve means being conditioned to communicate said vapor port with said fuel tank space and said charcoal canister when engine cranking operation occurs, said closed throttle producing a reduced vacuum within said intake manifold in response to engine cranking operations to produce a flow of vapor from said tank sapce and said charcoal canister into said manifold to precharge said intake manifold with vaporized fuel and air during engine cranking operation for improved engine ignition, means including a throttle position solenoid responsive to engine ignition to cause said throttle to move to an idle position so as to direct a predetermined quantity of the first predetermined air-fuel mixture from the carburetor into the intake manifold, said first valve means being conditioned in response to engine ignition to block communication between said canister and said intake manifold to reduce vaporized fuel enrichment of the intake manifold space when the first predetermined air-fuel mixture from said carburetor is directed across said idle positioned throttle, and means responsive to a predetermined engine temperature to condition said second valve means to block communication between said tank space and said intake manifold thereby to avoid excessive fuel vapor enrichment of the intake manifold when the engine has reached a predetermined operating temperature and is being fueled by the predetermined air-fuel mixture from the carburetor. 

1. In a vapor choke system for an internal combustion engine of the type including a throttle controlled air-fuel supply carburetor for fuel flow to an intake manifold the improvement comprising: means including a throttle position solenoid for closing the throttle during engine cranking operations, means defining a vapor port in communication with the intake manifold, a vaporized fuel air source, first vapor supply means having valve means therein to direct vapor from said source to said port, said valve means being conditioned opened when the throttle is closed to cause intake manifold vacuum produced by engine cranking to draw vapors from said source to produce a precharge of vaporized air-fuel in the intake manifold during engine cranking so as to produce improved cylinder combustion at engine start, and means responsive to engine start to condition said throttle positioning solenoid to open said throttle to a curb idle position, and means to sequentially modulate further vaporized air-fuel flow from said source to modulate the richness of fuel flow to the intake manifold in accordance with engine operating conditions.
 1. In a vapor choke system for an internal combustion engine of the type including a throttle controlled air-fuel supply carburetor for fuel flow to an intake manifold the improvement comprising: means including a throttle position solenoid for closing the throttle during engine cranking operations, means defining a vapor port in communication with the intake manifold, a vaporized fuel air source, first vapor supply means having valve means therein to direct vapor from said source to said port, said valve means being conditioned opened when the throttle is closed to cause intake manifold vacuum produced by engine cranking to draw vapors from said source to produce a precharge of vaporized air-fuel in the intake manifold during engine cranking so as to produce improved cylinder combustion at engine start, and means responsive to engine start to condition said throttle positioning solenoid to open said throttle to a curb idle position, and means to sequentially modulate further vaporized air-fuel flow from said source to modulate the richness of fuel flow to the intake manifold in accordance with engine operating conditions.
 2. An automotive vapor choke control system for an internal combustion engine comprising: a carburetor having a bore directed therethrough including an inlet end adapted to be connected to a source of air and an outlet end adapted to be connected to an intake manifold of a vehicle, a throttle valve located within said bore above said manifold, means for directing air-fuel mixture into said bore in accordance with engine operating conditions to provide a first predetermined air-fuel mixture flow into the intake manifold, means for positioning said throttle valve closed upon engine cranking operation, means defining a vapor port in communication with said bore between said throttle valve and the intake manifold, a source of vaporized fuel and air, first vapor supply means including valve means therein to control flow of vapor from said source to the vapor port, said valve means being conditioned to communicate said vapor port with said source of vaporized fuel and air when said throttle is closed whereby reduced intake manifold pressure produced by engine cranking operation will draw vapor from said source into said manifold to produce a vaporized precharge of fuel vapor in the intake manifold space during engine cranking so as to improve cylinder combustion at engine start, means responsive to engine ignition to open said throttle to a curb idle position, and means to produce a sequential control of vapor flow from said source to said vapor port so as to modulate the quantity of vapor fuel enrichment within said intake manifold in accordance with engine operating conditions. 